title: Methysergide blocks the sleep suppressant action of quipazine in rats.
abstract: The aim of the present study was to examine the effect of methysergide, a 5-hydroxytryptamine (5-HT) receptor antagonist, on the sleep suppression produced by the 5-HT receptor agonist, quipazine. Treatment with methysergide maleate (5 mg/kg, IP) 15 min before the administration of quipazine blocked quipazine-induced suppression of flow-wave sleep (SWS), but failed to prevent the decrease in rapid-eye-movement sleep (REMS) produced by quipazine. Treatment with methysergide also prevented the head-shaking behavior induced by quipazine, a phenomenon associated with increased activity of the central serotonergic system. Furthermore, it was shown that administration of methysergide alone (1 or 5 mg/kg, IP) had little effect on sleep or head-shaking behavior. The present data provide pharmacological evidence that the suppression of SWS but not REMS by quipazine may be a result of stimulation of 5-HT receptors.
mesh_terms: D000818:Animals; D004567:Electrodes, Implanted; D004576:Electromyography; D008297:Male; D008784:Methysergide / Q000494:pharmacology*; D011804:Quinolines / Q000037:antagonists & inhibitors*; D011814:Quipazine / Q000037:antagonists & inhibitors*; D051381:Rats; D011919:Rats, Inbred Strains; D012890:Sleep / Q000187:drug effects*; D012895:Sleep, REM / Q000187:drug effects; D013997:Time Factors
chemical_list: D011804:Quinolines; D011814:Quipazine; D008784:Methysergide